In the oilfield industry, various downhole tools (e.g., packers, bridge plugs, frac plugs) may be used to isolate sections of a wellbore. Such downhole tools may include a sealing element, which is generally made of rubber. The sealing element may initially be in a contracted configuration, allowing the downhole tool to be run into the wellbore without the sealing element scraping against the wellbore or any other surrounding tubular.
Upon reaching a desired location, such as an interface between two formation zones, the tool may be set. As part of the setting process, the sealing element may be expanded so as to seal with the wellbore wall (in the case of an open-hole tool) or with another surrounding tubular.
There are many different ways to expand the sealing element of a downhole tool. They include inflation, swelling, and mechanical setting, with there being many different designs for each. In particular, mechanical setting often involves squeezing the sealing element axially between two collars, so as to force the sealing element to deform and expand outwards. This may reliably set the tool, without have to employ fluids in the downhole environment to achieve setting.
One type of downhole tool is a packer, which generally isolates one section of a well annulus from another. Some packers are tailored for use in open-hole environments, i.e., wellbores and/or sections thereof that do not have a casing, liner, etc. between the packer and the wellbore wall. In these situations, the mechanical setting process may produce challenges. For example, open-hole packers are used in staged fracturing, allowing pressurized fluid to be injected into the annulus between the tubular and the wellbore in a specific zone, thereby fracturing the formation zone. During setting, however, the sealing element itself applies a load on the wellbore wall. This load may be additive with the load applied by the pressurized fluids, such that, when the pressurized fluid is injected, fractures tend to be concentrated near the packer.